Iran’s Hidden Path to the Bomb

To western officials who have spent months trying to slow down Iran’s nuclear program, Mahmoud Ahmadinejad’s announcement of plans to build ten new uranium enrichment plants is deeply unsettling. But the real worry may be the nuclear facilities already in existence. In mid-November, the Russian Energy Minister Sergei Shmatko announced that, for “technical reasons,” the Russians will not finish this year the reactor they are constructing for the Iranians at Bushehr on the Persian Gulf. Since the reasons were not given, one may speculate that, despite Russian denials, this is a message of displeasure sent to the Iranians.

There is much to be displeased about. One can make the case that the Bushehr reactor will be used for generating electricity, but no such case can be made for the reactor located at Arak in central Iran. While the Arak reactor is not powerful enough to generate meaningful amounts of electricity, it is far more powerful than is necessary to simply make medical isotopes—which the Iranians claim is its intended purpose. In fact, this reactor is suited to manufacture plutonium; it is a type that has been used in weapons programs in countries such as India and Israel.

During an August visit to Arak, the International Atomic Energy Agency inspectors were not able to verify whether the Iranian regime has the auxiliary equipment—for example the remote facilities—needed to separate plutonium from the reactor’s highly radioactive fuel elements. It is not certain when this reactor will go into operation but its existence is a red flag. Meanwhile, the centrifuge facility in Natanz is now operating with 3,936 P-1 centrifuges—the original type created with the help of A.Q. Khan, the Pakistani metallurgist and proliferator. There are, according to the IAEA, 4,456 additional centrifuges in the plant that are not yet operating for reasons unknown. Why is this worrisome?

The total production of low enriched uranium hexafluoride at Natanz has now reached over 1,700 kilograms. The thing to emphasize is that this is a drop in the bucket compared to the amount of low enriched uranium needed to power the Bushehr reactor, or any power reactor. In fact, the Russians were going to supply the Bushehr reactor with Russian-produced nuclear fuel, and the Arak reactor uses natural un-enriched uranium. The only use one can imagine, then, for the low-enriched uranium produced at Natanz would be to further enrich it in order to obtain uranium 235, the rare isotope needed for a fission reaction. If it were enriched to about 20 percent uranium 235 it could be used to power the research reactor at Tehran University. If it were clandestinely enriched to 95 percent it could be used in one or two weapons.

In this regard, the most troubling development is Iran’s disclosure earlier this autumn of a heretofore clandestine centrifuge plant near the city of Qom. The IAEA inspectors found this facility to be in an advanced state of preparation for the installation of some 3,000 centrifuges. If these are of the new carbon fiber type they have twice the separative capacity of the P-1—allowing them to enrich uranium much more rapidly. Depending on how these centrifuges are configured, they can enrich enough uranium for two or more bombs a year. There is little doubt that the Iranians purchased the plans for a nuclear device from A.Q. Khan. But with or without such plans the Iranians are quite capable of making their own.

Now the Iranians have announced they will build several more enrichment facilities involving tens of thousands of centrifuges. The IAEA inspectors were never allowed to visit the plants where Iran is manufacturing its centrifuges but it is very unlikely that the Iranians have the material to build the quantity required for these planned facilities. Their supply of uranium is also not unlimited.

In my view the real immediate danger is at Natanz. Here is the issue: there are mumblings from the Iranians that they are going to pull out of the non-proliferation treaty and begin enriching uranium to higher levels. Depending on the sophistication of the design, you need between 18 and 30 kilograms of uranium 235 to make a bomb. The uranium hexafluoride gas at Natanz, from which the uranium 235 would be extracted, has now been enriched to about 3.5 percent uranium 235. The quickest way to enrich this to the 90 percent required in a bomb is what it called “batch recycling”: the existing stock of low-enriched uranium can be recycled a few times back through the existing centrifuge cascade, acquiring a higher percentage of uranium 235 with each cycle. There is enough available stock to make one or two bombs by the recycling method; enough for one bomb’s worth could be achieved in as little as six months.

The cover for this plan would be the claim that they are doing enrichment only to the 20 percent needed for the Tehran Research Reactor. But once this genie is out of the bottle nothing will stop them from going all the way. So the question is do they have enough low-enriched uranium to use to make the 18 to 30 kilograms of uranium 235 that, depending on the sophistication of the design, are needed to make a bomb? It would appear that they do. And if they pursue the batch-recycling method, time is rapidly running out.